Method, apparatus and system for detecting location of laser point on screen

ABSTRACT

A method for detecting a location of a laser point on a screen includes acquiring a first image frame captured by a first camera among N cameras; detecting whether a first laser point exists in the first image frame; and when the first laser point exists in the first image frame, and no laser point exists in an image frame captured by another camera except the first camera among the N cameras, using the first laser point as the laser point on the screen, and acquiring information about a location of the first laser point on the screen. In the present application, images captured by all cameras do not need to be fused first; instead, laser point detection is performed directly on a captured image frame. This greatly improves efficiency of the laser point detection and improves detection accuracy.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Chinese Patent Application No.201510490798.7, filed on Aug. 11, 2015, which is hereby incorporated byreference in its entirety.

TECHNICAL FIELD

Embodiments of the present application relate to the communicationstechnologies, and in particular, to a method, an apparatus and a systemfor detecting a location of a laser point on a screen.

BACKGROUND

At present, a laser pointer is an interactive device commonly used in aprojection screen display system. A laser emitted by the laser pointerprojects a laser point onto the screen, and control over a projectiondevice can be effectively implemented by detecting, using a camera, amovement of the laser point on the screen.

As a projected area increases, it is difficult for a single camera tocover an entire screen. Multiple cameras are used to capture an image onthe screen, and each of the cameras is responsible for capturing animage in one area on the screen. First, image fusion is performed on anoverlapping area captured by different cameras; then laser pointdetection is performed on an entire frame to determine a location of alaser point; finally, information about the location of the laser pointis output by means of coordinate transformation.

However, each time an image is captured, image fusion needs to beperformed first, and then laser point detection is performed on anentire frame. This results in extremely poor real-time performance in anentire process of acquiring a location of a laser point.

SUMMARY

The present application provides a method, an apparatus and a system fordetecting a location of a laser point on a screen, so as to solve aproblem of poor real-time performance of location acquiring during laserpoint detection on a projection screen.

A first aspect of embodiments of the present application provides amethod for detecting a location of a laser point on a screen, where themethod is applied to a screen projection system, the system includes ascreen and N cameras, the screen includes N screen areas, the N camerasare used to capture images in the N screen areas, the screen areascorrespond to the cameras in a one-to-one manner, N is a positiveinteger greater than 1, and the method includes acquiring a first imageframe captured by a first camera among the N cameras; detecting whethera first laser point exists in the first image frame; and when the firstlaser point exists in the first image frame, and no laser point existsin an image frame captured by another camera except the first cameraamong the N cameras, using the first laser point as a laser point on thescreen, and acquiring information about a location of the first laserpoint on the screen.

With reference to the first aspect, in a first possible implementationmanner of the first aspect, when laser points exist in at least twoprevious image frames of the first image frame, the detecting whether afirst laser point exists in the first image frame includes determining amotion tendency of a laser point in a first screen area among the Nscreen areas according to information about locations of the laserpoints in the at least two previous image frames, where the first imageframe includes an image in the first screen area; determining a firstdetection area in the first image frame according to the motiontendency; and detecting whether the first laser point exists in thefirst detection area.

With reference to the first possible implementation manner of the firstaspect, in a second possible implementation manner of the first aspect,the detecting whether the first laser point exists in the firstdetection area includes detecting whether a first pixel exists in thefirst detection area, where pixels constituting the first laser pointinclude the first pixel; and correspondingly, the acquiring informationabout a location of the first laser point on the screen includesdetermining a second detection area in the first image frame accordingto information about a location of the first pixel in the first imageframe; detecting a second pixel in the second detection area, where thepixels constituting the first laser point include the second pixel, andacquiring information about a location of the second pixel in the firstimage frame; and acquiring the information about the location of thefirst laser point on the screen according to the information about thelocation of the second pixel in the first image frame.

With reference to the first aspect, in a third possible implementationmanner of the first aspect, the detecting whether a first laser pointexists in the first image frame includes determining a scanning area inthe first image frame; performing downsampling on the scanning area byusing m rows as a vertical sampling interval and n columns as ahorizontal sampling interval to obtain a downsampling result, where m isa positive integer, and n is a positive integer; and detecting whetherthe first laser point exists in the downsampling result.

With reference to the third possible implementation manner of the firstaspect, in a fourth possible implementation manner of the first aspect,the downsampling result includes a low-resolution image frame obtainedafter the downsampling is performed on the scanning area; and theacquiring information about a location of the first laser point on thescreen includes acquiring information about a low-resolution location ofthe first laser point in the low-resolution image frame; determining apotential area in the first image frame, where the potential areacorresponds to the information about the low-resolution location;detecting the first laser point in the potential area, and acquiringinformation about a location of the first laser point in the first imageframe; and acquiring the information about the location of the firstlaser point on the screen according to the information about thelocation of the first laser point in the first image frame.

With reference to any one of the first aspect to the fourth possibleimplementation manner of the first aspect, in a fifth possibleimplementation manner of the first aspect, the method further includes,when a second laser point exists in a second image frame captured by asecond camera among the N cameras, acquiring information about alocation, on the screen, of the laser point on the screen according tothe first laser point and the second laser point.

With reference to the fifth possible implementation manner of the firstaspect, in a sixth possible implementation manner of the first aspect,the acquiring information about a location, on the screen, of the laserpoint on the screen according to the first laser point and the secondlaser point includes determining the laser point on the screen from thefirst laser point and the second laser point; and acquiring theinformation about the location, on the screen, of the laser point on thescreen.

With reference to the sixth possible implementation manner of the firstaspect, in a seventh implementation manner of the first aspect, when thelaser points exist in the at least two previous image frames of thefirst image frame that is captured by the first camera, the determiningthe laser point on the screen from the first laser point and the secondlaser point includes using the first laser point as the laser point onthe screen when the motion tendency of the laser point in the firstscreen area among the N screen areas is from the first screen area to asecond screen area among the N screen areas, where the motion tendencyis obtained according to the information about the locations of thelaser points in the at least two previous image frames, the first imageframe includes the image in the first screen area, and the second imageframe includes an image in the second screen area; or using the secondlaser point as the laser point on the screen when the motion tendency isfrom a second screen area to the first screen area.

With reference to the fifth possible implementation manner of the firstaspect, in an eighth possible implementation manner of the first aspect,the acquiring information about a location, on the screen, of the laserpoint on the screen according to the first laser point and the secondlaser point includes determining whether the first laser point and thesecond laser point are a same laser point according to first locationinformation of the first laser point and second location information ofthe second laser point, where the first location information is theinformation about the location of the first laser point in the firstimage frame, the second location information is information about alocation of the second laser point in the second image frame, the secondimage frame includes an image in a second screen area among the N screenareas, the first image frame includes the image in the first screen areaamong the N screen areas, and the second screen area is adjacent to thefirst screen area; and when the first laser point and the second laserpoint are the same laser point, acquiring the information about thelocation, on the screen, of the laser point on the screen according tothe first location information and the second location information.

With reference to any one of the first aspect to the eighth possibleimplementation manner of the first aspect, in a ninth possibleimplementation manner of the first aspect, the first camera is awide-angle camera; and before the acquiring information about a locationof the first laser point on the screen, the method further includescalibrating the first location information to calibrate a distortionresulting from the wide-angle camera, so that the information about thelocation, on the screen, of the laser point on the screen is acquiredaccording to the calibrated location information, where the firstlocation information is the information about the location of the firstlaser point in the first image frame.

A second aspect of the embodiments of the present application providesan apparatus for detecting a location of a laser point on a screen,where the apparatus is applied to a screen projection system, the systemincludes a screen and N cameras, the screen includes N screen areas, theN cameras are used to capture images in the N screen areas, the screenareas correspond to the cameras in a one-to-one manner, N is a positiveinteger greater than 1, and the apparatus includes a first acquiringmodule configured to acquire a first image frame captured by a firstcamera among the N cameras; a detection module configured to detectwhether a first laser point exists in the first image frame acquired bythe first acquiring module; and a second acquiring module configured to,when the detection module determines that the first laser point existsin the first image frame, and no laser point exists in an image framecaptured by another camera except the first camera among the N cameras,use the first laser point as a laser point on the screen, and acquireinformation about a location of the first laser point on the screen.

With reference to the second aspect, in a first possible implementationmanner of the second aspect, the detection module is configured to, whenlaser points exist in at least two previous image frames of the firstimage frame, determine a motion tendency of a laser point in a firstscreen area among the N screen areas according to information aboutlocations of the laser points in the at least two previous image frames,where the first image frame includes an image in the first screen area;determine a first detection area in the first image frame according tothe motion tendency; and detect whether the first laser point exists inthe first detection area.

With reference to the first possible implementation manner of the secondaspect, in a second possible implementation manner of the second aspect,the detection module is configured to detect whether a first pixelexists in the first detection area, where pixels constituting the firstlaser point include the first pixel; and correspondingly, the secondacquiring module is configured to determine a second detection area inthe first image frame according to information about a location of thefirst pixel in the first image frame; detect a second pixel in thesecond detection area, where the pixels constituting the first laserpoint include the second pixel, and acquire information about a locationof the second pixel in the first image frame; and acquire theinformation about the location of the first laser point on the screenaccording to the information about the location of the second pixel inthe first image frame.

With reference to the second aspect, in a third possible implementationmanner of the second aspect, the detection module is configured todetermine a scanning area in the first image frame; perform downsamplingon the scanning area by using m rows as a vertical sampling interval andn columns as a horizontal sampling interval to obtain a downsamplingresult, where m is a positive integer, and n is a positive integer; anddetect whether the first laser point exists in the downsampling result.

With reference to the third possible implementation manner of the secondaspect, in a fourth possible implementation manner of the second aspect,the downsampling result includes a low-resolution image frame acquiredafter the downsampling is performed on the scanning area; and the secondacquiring module is configured to acquire information about alow-resolution location of the first laser point in the low-resolutionimage frame; determine a potential area in the first image frame, wherethe potential area corresponds to the information about thelow-resolution location; detect the first laser point in the potentialarea, and acquire information about a location of the first laser pointin the first image frame; and acquire the information about the locationof the first laser point on the screen according to the informationabout the location of the first laser point in the first image frame.

With reference to any one of the second aspect to the fourth possibleimplementation manner of the second aspect, in a fifth possibleimplementation manner of the second aspect, the second acquiring moduleis further configured to, when a second laser point exists in a secondimage frame captured by a second camera among the N cameras, acquireinformation about a location, on the screen, of the laser point on thescreen according to the first laser point and the second laser point.

With reference to the fifth possible implementation manner of the secondaspect, in a sixth possible implementation manner of the second aspect,the second acquiring module is configured to determine the laser pointon the screen from the first laser point detected by the detectionmodule and the second laser point; and acquire the information about thelocation, on the screen, of the laser point on the screen.

With reference to the sixth possible implementation manner of the secondaspect, in a seventh possible implementation manner of the secondaspect, the second acquiring module is configured to, when the laserpoints exist in the at least two previous image frames of the firstimage frame that is captured by the first camera, use the first laserpoint as the laser point on the screen when the motion tendency of thelaser point in the first screen area among the N screen areas is fromthe first screen area to a second screen area among the N screen areas,where the motion tendency is obtained according to the information aboutthe locations of the laser points in the at least two previous imageframes, the first image frame includes the image in the first screenarea, and the second image frame includes an image in the second screenarea; or use the second laser point as the laser point on the screenwhen the motion tendency is from a second screen area to the firstscreen area.

With reference to any one of the second aspect to the fifth possibleimplementation manner of the second aspect, in an eighth possibleimplementation manner of the second aspect, the second acquiring moduleis configured to determine whether the first laser point and the secondlaser point are a same laser point according to first locationinformation of the first laser point detected by the detection moduleand second location information of the second laser point, where thefirst location information is the information about the location of thefirst laser point in the first image frame, the second locationinformation is information about a location of the second laser point inthe second image frame, the second image frame includes an image in asecond screen area among the N screen areas, the first image frameincludes the image in the first screen area among the N screen areas,and the second screen area is adjacent to the first screen area; andwhen the first laser point and the second laser point are the same laserpoint, acquire the information about the location, on the screen, of thelaser point on the screen according to the first location informationand the second location information.

With reference to any one of the second aspect to the eighth possibleimplementation manner of the second aspect, in a ninth possibleimplementation manner of the second aspect, the first camera is awide-angle camera; and the apparatus further includes a calibrationmodule configured to calibrate the first location information tocalibrate a distortion resulting from the wide-angle camera, so that thesecond acquiring module acquires the information about the location, onthe screen, of the laser point on the screen according to the calibratedlocation information, where the first location information is theinformation about the location of the first laser point in the firstimage frame.

A third aspect of the present application provides a screen projectionsystem, including a screen, the apparatus for detecting a location of alaser point on a screen according to any one of the second aspect to theeighth possible implementation manner of the second aspect, and Ncameras, where N is a positive integer greater than 1; and the screenincludes N screen areas, the N cameras capture images in the N screenareas, and the screen areas correspond to the cameras in a one-to-onemanner.

With reference to the third aspect, in a first possible implementationmanner of the third aspect, the system includes N projection devices,the N screen areas are N subscreens, the screen is a spliced projectionscreen including the N subscreens, the subscreens correspond to theprojection devices in a one-to-one manner, and no overlapping areaexists between respective projection areas of the N projection devices.

With reference to the third aspect or the first possible implementationmanner of the third aspect, in a second possible implementation mannerof the third aspect, the system further includes a synchronizationapparatus, where the synchronization apparatus connects to the Ncameras, and the synchronization apparatus is configured to control theN cameras to capture the images in the N screen areas at the same time.

With reference to any one of the third aspect to the second possibleimplementation manner of the third aspect, in a third possibleimplementation manner of the third aspect, no overlapping area existsbetween the respective images captured by the N cameras.

According to the method, the apparatus and the system for detecting alocation of a laser point on a screen provided in the embodiments of thepresent application, images captured by all cameras do not need to befused first; instead, laser point detection is performed directly on acaptured image frame. This greatly improves real-time performance oflocation acquiring during the laser point detection.

BRIEF DESCRIPTION OF THE DRAWINGS

To describe the technical solutions in the embodiments of the presentapplication more clearly, the following briefly introduces theaccompanying drawings required for describing the embodiments. Theaccompanying drawings in the following description show some embodimentsof the present application, and persons of ordinary skill in the art maystill derive other drawings from these accompanying drawings withoutcreative efforts.

FIG. 1 is a schematic flowchart of Embodiment 1 of a method fordetecting a location of a laser point on a screen according to thepresent application;

FIG. 2 is a schematic flowchart of Embodiment 2 of a method fordetecting a location of a laser point on a screen according to thepresent application;

FIG. 3 is a schematic flowchart of Embodiment 3 of a method fordetecting a location of a laser point on a screen according to thepresent application;

FIG. 4 is a schematic diagram of an image resolution change in a methodfor detecting a location of a laser point on a screen according to thepresent application;

FIG. 5 is a schematic flowchart of Embodiment 4 of a method fordetecting a location of a laser point on a screen according to thepresent application;

FIG. 6 is a schematic diagram of coordinate fusion in a method fordetecting a location of a laser point on a screen according to thepresent application;

FIG. 7 is a schematic diagram of coordinate fusion in a method fordetecting a location of a laser point on a screen according to thepresent application;

FIG. 8 is a schematic structural diagram of Embodiment 1 of an apparatusfor detecting a location of a laser point on a screen according to thepresent application;

FIG. 9 is a schematic structural diagram of Embodiment 2 of an apparatusfor detecting a location of a laser point on a screen according to thepresent application;

FIG. 10 is a schematic structural diagram of Embodiment 3 of anapparatus for detecting a location of a laser point on a screenaccording to the present application; and

FIG. 11 is a schematic structural diagram of Embodiment 1 of a screenprojection system according to the present application.

DETAILED DESCRIPTION

To make the objectives, technical solutions, and advantages of theembodiments of the present application clearer, the following clearlydescribes the technical solutions in the embodiments of the presentapplication with reference to the accompanying drawings in theembodiments of the present application. The described embodiments aresome but not all of the embodiments of the present application. Allother embodiments obtained by persons of ordinary skill in the art basedon the embodiments of the present application without creative effortsshall fall within the protection scope of the present application.

A screen projection system in an embodiment of the present applicationmay include a screen, a laser pointer, N cameras, a projection device,and an apparatus for detecting a location of a laser point on a screen,where the screen receives an image projected by the projection device,the laser pointer projects a laser point onto the screen, the camerascapture the image on the screen and output the image to the apparatusfor detecting a location of a laser point on a screen, and the apparatusfor detecting a location of a laser point on a screen acquirescoordinates of the laser point on the image by means of processing. Thescreen may include N screen areas. The screen may be an entire screen ormay be a spliced projection screen obtained by splicing multiplesubscreens. A principle of acquiring the coordinates of the laser pointon the entire screen is basically the same as a principle of acquiringthe coordinates of the laser point on the spliced projection screen.Light filters may be disposed on the cameras to obtain an image with ahigh signal-to-noise ratio.

FIG. 1 is a schematic flowchart of Embodiment 1 of a method fordetecting a location of a laser point on a screen according to thepresent application. In this embodiment, the screen includes N screenareas, N cameras are used to capture images in the N screen areas, thescreen areas correspond to the cameras in a one-to-one manner, and N isa positive integer greater than 1.

Each of the cameras transmits a captured image to an apparatus fordetecting a location of a laser point on a screen, where the apparatussits in the background. The apparatus for detecting a location of alaser point on a screen separately processes the image transmitted byeach of the cameras, so as to detect a laser point. An image captured byanother camera is not considered in a process of detecting the laserpoint.

In this embodiment, one or more projection devices may be available. Ifmultiple projection devices are available, each of the projectiondevices may correspond to one or more screen areas and project an imagein a corresponding screen area.

The method may be performed by the apparatus for detecting a location ofa laser point on a screen, and the apparatus for detecting a location ofa laser point on a screen may be a processing device such as a computeror a notebook computer. As shown in FIG. 1, the method includes thefollowing steps.

S101. Acquire a first image frame captured by a first camera among the Ncameras. The first camera corresponds to a first screen area, the firstimage frame includes an image in the first screen area, and the firstcamera is one of the N cameras.

The first camera may be any one of the N cameras.

S102. Detect whether a first laser point exists in the first imageframe.

S103. When the first laser point exists in the first image frame, and nolaser point exists in an image frame captured by another camera exceptthe first camera among the N cameras, use the first laser point as thelaser point on the screen, and acquire information about a location ofthe first laser point on the screen. That is, use the first laser pointas a laser point actually projected by a laser pointer onto the screen,where the information about the location may be a coordinate value.

An image captured by the another camera includes an image in anotherscreen area except the first screen area among the N screen areas.

During acquiring the information about the location of the first laserpoint on the screen, information about a location of the first laserpoint in the first image frame is acquired first, that is, informationabout coordinates of the first laser point in a camera coordinate systemis acquired, and then the information about the coordinates of the firstlaser point in the camera coordinate system is converted intoinformation about coordinates in a screen display coordinate systemaccording to a mapping relationship between the camera coordinate systemand the screen display coordinate system, where the information aboutthe coordinates of the first laser point in the screen displaycoordinate system is the information about the location of the firstlaser point on the screen.

It should be noted that the apparatus for detecting a location of alaser point on a screen may simultaneously process images captured bythe N cameras, that is, perform laser point detection separately inimage frames captured by the N cameras; determine, after detecting thefirst laser point, whether a laser point is detected in the image framecaptured by the another camera among the N cameras; and if no laserpoint is detected in the image frame captured by the another cameraamong the N cameras, directly determine that the first laser point isthe laser point on the screen, and acquire the information about thelocation of the first laser point on the screen.

When multiple cameras capture images, it is impossible to have acompletely clear boundary, and therefore an overlapping area may existwhen images in adjacent areas are captured. That is, when capturing animage in an adjacent second screen area, a second camera may alsocapture a part of the image in the first screen area, where the image inthe first screen area is captured by the first camera second screenarea. Therefore, after a laser point is detected, information about anactual location of the laser point can be determined in a more accuratemanner by considering whether a laser point exists in the image capturedby the another camera.

In this embodiment, a first image frame captured by a first camera isacquired; whether a first laser point exists in the first image frame isdetected; and when the first laser point exists in the first imageframe, and no laser point exists in an image captured by another cameraexcept the first camera among N cameras, it is determined that the firstlaser point is a laser point on a screen, and information about alocation of the first laser point on the screen is acquired. That is,images captured by all cameras do not need to be fused first; instead,laser point detection is directly performed on a captured image frame.This greatly improves efficiency of the laser point detection andimproves detection accuracy.

FIG. 2 is a schematic flowchart of Embodiment 2 of a method fordetecting a location of a laser point on a screen according to thepresent application. As shown in FIG. 2, if laser points exist in atleast two previous image frames of the first image frame, the detectingwhether a first laser point exists in the first image frame includes thefollowing steps.

S201. Determine a motion tendency of a laser point in a first screenarea among the N screen areas according to information about locationsof the laser points in the at least two previous image frames, where thefirst image frame includes an image in the first screen area; anddetermine a first detection area in the first image frame according tothe motion tendency.

When capturing an image, a camera may continuously capture multipleframes of images. The previous image frames refer to image framescaptured by the first camera before the first image frame is captured.The motion tendency of the laser point may be determined according tothe laser points detected in the previous image frames; a possiblelocation of the laser point is further acquired as a predicted location;and a particular range is extended using the predicted location as acenter, and an area in the range is used as the first detection area.

A previous image frame may be only an image of one frame prior to thefirst image frame, that is, the first detection area may bealternatively determined based on an image of one previous frame.

S202. Detect whether the first laser point exists in the first detectionarea. If no laser point exists, a detection method shown in FIG. 3 maybe further performed.

It should be noted that the detecting whether the first laser pointexists in the first detection area may be scanning a pixel point in thefirst detection area, and acquiring a grayscale value of the scannedpixel point, where if the grayscale value is greater than or equal to apreset threshold, it is determined that the pixel point belongs to thelaser point, and if the grayscale value is less than the presetthreshold, it indicates that no laser point exists on the pixel point,which, however, is not limited herein. When the first laser point existsin the first detection area, the first laser point exists in the firstimage frame.

Further, the determining the information about the location of the firstlaser point in the first image frame may be narrowing down the firstdetection area, and detecting information about a location of the firstlaser point in a narrowed-down first detection area.

The detecting whether the first laser point exists in the firstdetection area includes detecting whether a first pixel exists in thefirst detection area, where pixels constituting the first laser pointinclude the first pixel; stopping the detection after the first pixel isdetected, and determining a second detection area in the first imageframe according to information about a location of the first pixel inthe first image frame; detecting a second pixel in the second detectionarea, where the pixels constituting the first laser point include thesecond pixel, and acquiring information about a location of the secondpixel in the first image frame; and acquiring the information about thelocation of the first laser point on the screen according to theinformation about the location of the second pixel in the first imageframe.

The second detection area may be smaller than the first detection area,and a location of the second detection area may also be different fromthat of the first detection area. A method for acquiring the informationabout the location of the first laser point on the screen may beaveraging information about locations of second pixels as theinformation about the location of the first laser point in the firstimage frame, and acquiring the information about the location of thefirst laser point on the screen according to the mapping relationshipbetween the camera coordinate system and the screen display coordinatesystem. The second pixels may include the first pixel or may have or nothave an intersection set with the first pixel. A quantity of firstpixels may be 1 or 2. A quantity of second pixels may be greater thanthat of first pixels.

FIG. 3 is a schematic flowchart of Embodiment 3 of a method fordetecting a location of a laser point on a screen according to thepresent application. In an initial state, if no laser point is detectedin a previous image frame of the first image frame, a laser point may bedetected by using the method in FIG. 3. In addition, the method shown inFIG. 3 may be further used to detect a laser point if no laser point isdetected in the first image frame by using the method shown in FIG. 2.

As shown in FIG. 3, the detecting whether a laser point exists in thefirst image frame may be the following.

S301. Determine a scanning area in the first image frame.

In the initial state, no previous image frame is captured, and no otherreference is available. Therefore, in this case, a relatively largescanning area may be determined, for example, the entire first imageframe may be used as the scanning area.

If no laser point is detected in the first image frame by using themethod shown in FIG. 2, a range of the foregoing first detection areamay be extended, and a remaining area after the original first detectionarea is excluded from the extended range is used as the scanning area.

S302. Perform downsampling on the scanning area by using m rows as avertical sampling interval and n columns as a horizontal samplinginterval to obtain a downsampling result, where m is a positive integer,and n is a positive integer; and detect whether the first laser pointexists in the downsampling result.

When the first laser point exists in the downsampling result, the firstlaser point exists in the first image frame. FIG. 4 is a schematicdiagram of an image resolution change in a method for detecting alocation of a laser point on a screen according to the presentapplication. FIG. 5 is a schematic flowchart of Embodiment 4 of a methodfor detecting a location of a laser point on a screen according to thepresent application.

The downsampling result includes a low-resolution image frame obtainedafter downsampling is performed on the first image frame. For example,an image frame whose resolution is 250*250 is obtained by performingdownsampling on the first image frame whose original resolution is500*500. Correspondingly, the acquiring information about a location ofthe first laser point on the screen includes the following steps.

S501. Acquire information about a low-resolution location of the firstlaser point in the low-resolution image frame.

S502. Determine a potential area in the first image frame, where thepotential area corresponds to the information about the low-resolutionlocation.

Referring to FIG. 4, scanning is performed after the low-resolutionimage frame is acquired, to detect a laser point. It may bealternatively determined according to a grayscale value of a scannedpixel point. If the grayscale value is greater than or equal to a presetthreshold, it is determined that the pixel point belongs to the laserpoint; if the grayscale value is less than the preset threshold, itindicates that no laser point exists on the pixel point, which, however,is not limited herein.

S503. Detect the first laser point in the potential area, and acquireinformation about a location of the first laser point in the first imageframe; and acquire the information about the location of the first laserpoint on the screen according to the information about the location ofthe first laser point in the first image frame.

Referring to FIG. 4, coordinates or a size of the first laser point maybe determined in the low-resolution image frame first, then thepotential area in the first image frame is deduced according to amapping relationship between the low-resolution image frame and thefirst image frame or according to a downsampling frequency, and thefirst laser point is determined in the potential area. The informationabout the location of the first laser point in the first image frame isacquired first, and then the information about the location of the firstlaser point on the screen is acquired.

In another embodiment, when a second laser point exists in a secondimage frame captured by a second camera among the N cameras, informationabout a location, on the screen, of the laser point on the screen may beacquired according to the first laser point and the second laser point,where the second camera corresponds to a second screen area, and thesecond image frame includes an image in the second screen area.

A method for acquiring the information about the location, on thescreen, of the laser point on the screen may be determining the laserpoint on the screen from the first laser point and the second laserpoint; and acquiring the information about the location, on the screen,of the laser point on the screen. That is, an actual laser point on thescreen is determined first according to the first laser point and thesecond laser point, and then information about a location of the actuallaser point is acquired.

The determining the laser point on the screen from the first laser pointand the second laser point may be using the first laser point as thelaser point on the screen when the motion tendency of the laser point inthe first screen area among the N screen areas is from the first screenarea to the second screen area among the N screen areas, where themotion tendency is obtained according to the information about thelocations of the laser points in the at least two previous image frames,the first image frame includes the image in the first screen area, andthe second image frame includes the image in the second screen area; orusing the second laser point as the laser point on the screen when themotion tendency is from the second screen area to the first screen area.

For the screen, when capturing images in adjacent areas, the cameras maycapture images in areas partially overlapping each other, that is, whencapturing the image in the first screen area, the first camera may alsocapture a part of the image in the adjacent second screen area. This mayresult in that laser points exist in the images captured by the twocameras. In this case, an accurate location of the laser point needs tobe determined. After the first image frame is fused with the secondimage frame, when both the first laser point and the second laser pointare located in an overlapping area of the first image frame and thesecond image frame, the laser point on the screen may be alternativelydetermined according to the method for determining the laser point onthe screen from the first laser point and the second laser point.

In the initial state, if no previous image frame is available, theactual laser point may be not determined temporarily and is to bedetermined after an image frame is captured subsequently, which,however, is not limited herein. The actual laser point may be determinedby using other methods.

Based on the foregoing embodiment, in another embodiment, the method foracquiring the information about the location, on the screen, of thelaser point on the screen according to the first laser point and thesecond laser point may also be determining whether the first laser pointand the second laser point are a same laser point according to firstlocation information of the first laser point and second locationinformation of the second laser point, where the first locationinformation is the information about the location of the first laserpoint in the first image frame, the second location information is theinformation about the location of the second laser point in the secondimage frame, the second image frame includes the image in the secondscreen area among the N screen areas, the first image frame includes theimage in the first screen area among the N screen areas, the secondscreen area may be or not be adjacent to the first screen area, and theadjacency may be having a common edge or a common vertex; and when thefirst laser point and the second laser point are the same laser point,acquiring the information about the location, on the screen, of thelaser point on the screen according to the first location informationand the second location information.

The N screen areas may be N subscreens, and the screen is a splicedprojection screen including the N subscreens. Optionally, the Nsubscreens receive images projected by N projection devices, where the Nprojection devices correspond to the N subscreens in a one-to-onemanner. In addition, the N cameras capture images on the N subscreens.In such a screen system, the N cameras capture the images on the Nsubscreens at the same time to ensure accuracy of subsequently acquiredlaser point coordinates and further reduce time for subsequentcoordinate fusion. In specific implementation, the N cameras may furtherbe connected to a synchronization apparatus, and the synchronizationapparatus may send a pulse signal to the N camera to control the Ncameras to capture the images on the N subscreens at the same time. Inthis embodiment, it is further supported that at least one laser pointeremits a laser point onto the spliced projection screen at the same time.

The synchronization apparatus may be a same device as the apparatus fordetecting a location of a laser point on a screen; for example, both usea computer device.

FIG. 6 is a schematic diagram of coordinate fusion in a method fordetecting a location of a laser point on a screen according to thepresent application.

Based on the spliced projection screen, a gap exists between thesubscreens, and therefore a boundary is more easily marked when thecameras capture the images on the subscreens. Marking may be performedby using a middle point of the gap to prevent a camera from capturing animage on an adjacent subscreen. However, in some special cases in which,for example, a laser point happens to be in the middle of a gap betweenadjacent subscreens, a part of the laser point exists in the first imageframe captured by the first camera in the first screen area, and a partof the laser point also exists in the second image frame captured by thesecond camera in the adjacent second screen area. Therefore, an accuratelocation of the laser point needs to be further determined by means ofcoordinate fusion. When the second laser point exists in the secondimage frame captured by the second camera among the N cameras, whetherthe first laser point and the second laser point are the same laserpoint is determined according to the first location information of thefirst laser point and the second location information of the secondlaser point. When the first laser point and the second laser point arethe same laser point, the information about the location of the laserpoint on the screen is acquired according to the first locationinformation and the second location information.

If the first laser point and the second laser point are not the samelaser point, it indicates that they may be laser points emitted by twolaser pointers, that is, two target laser points exist. In this case,both the first location information and the second location informationare information about locations, in the image frames, of actual laserpoints on the screen, and location information corresponding to thefirst location information and location information corresponding to thesecond location information are acquired from the screen coordinatesystem.

It should be noted that the first location information is theinformation about the location of the first laser point in the firstimage frame, and the second location information is the informationabout the location of the second laser point in the second image frame.The second camera corresponds to the second screen area, the first imageframe includes the image in the first screen area, and the second imageframe includes the image in the second screen area.

Referring to FIG. 6, it is assumed that a first laser point 01 isdetected in the first image frame, and a second laser point 02 isdetected in the second image frame. FIG. 6 shows correspondingcoordinates of the first laser point 01 and the second laser point 02 inthe first image frame and the second image frame respectively. The firstlaser point 01 is recorded as (x1, y1), the second laser point 02 isrecorded as (x2, y2), and d2 is a duplication determining threshold. Anabsolute value d of a difference between the first laser point 01 andthe second laser point 02 is calculated, that is, d=|(x1, y1)−(x2, y2)|,and if d is less than d2, the first laser point and the second laserpoint are the same laser point. In this case, valid location information(x0, y0) is calculated, and the valid location information isinformation about a location, in a captured image frame, of an actuallaser point on the screen, that is, the location information in thecamera coordinate system. Further, the information about the location ofthe laser point on the screen is acquired by means of coordinatetransformation.

x0=x1*w1+x2*w2, and y0=y1*w1+y2*w2, where * is a multiple sign, and w1and w2 are weight values. The d2 may be an empirical value or may beadjusted according to an actual detection result.

FIG. 7 is a schematic diagram of coordinate fusion in a method fordetecting a location of a laser point on a screen according to thepresent application. FIG. 7 is similar to FIG. 6 except that laserpoints are detected on four adjacent subscreens. A method for fusingcoordinates of the laser points is similar to the method used when twolaser points are detected, and details are not described herein again.

Based on the embodiment, if the method is applied to a short-focusprojection screen system, that is, a camera is extremely near a screen,an image needs to be captured by using a wide-angle camera for a purposeof acquiring a more complete and accurate image. If the camera is thewide-angle camera, before the information about the location of thefirst laser point on the screen is acquired, the first locationinformation is calibrated to calibrate a distortion resulting from thewide-angle camera, so that the information about the location, on thescreen, of the laser point on the screen is acquired according to thecalibrated location information, where the first location information isthe information about the location of the first laser point in the firstimage frame.

FIG. 8 is a schematic structural diagram of Embodiment 1 of an apparatusfor detecting a location of a laser point on a screen according to thepresent application. The apparatus for detecting a location of a laserpoint on a screen may be the apparatus for detecting a location of alaser point on a screen in the screen projection system. The screenincludes N screen areas, N cameras are used to capture images in the Nscreen areas, the screen areas correspond to the cameras in a one-to-onemanner, and N is a positive integer greater than 1.

As shown in FIG. 8, the apparatus includes a first acquiring module 801,a detection module 802, and a second acquiring module 803.

The first acquiring module 801 is configured to acquire a first imageframe captured by a first camera among the N cameras, where the firstcamera corresponds to a first screen area, the first image frameincludes an image in the first screen area, and the first camera is oneof the N cameras.

The detection module 802 is configured to detect whether a first laserpoint exists in the first image frame acquired by the first acquiringmodule.

The second acquiring module 803 is configured to, when the detectionmodule determines that the first laser point exists in the first imageframe, and no laser point exists in an image frame captured by anothercamera except the first camera among the N cameras, use the first laserpoint as the laser point on the screen, and acquire information about alocation of the first laser point on the screen.

In this embodiment, a first image frame captured by a first camera isacquired; whether a first laser point exists in the first image frame isdetected; and when the first laser point exists in the first imageframe, and no laser point exists in an image captured by another cameraexcept the first camera among N cameras, it is determined that the firstlaser point is a laser point on a screen, and information about alocation of the first laser point on the screen is acquired. That is,images captured by all cameras do not need to be fused first; instead,laser point detection is directly performed on a captured image frame.This greatly improves efficiency of the laser point detection andimproves detection accuracy.

Further, the detection module 802 is configured to, when laser pointsexist in at least two previous image frames of the first image frame,determine a motion tendency of a laser point in the first screen areaamong the N screen areas according to information about locations of thelaser points in the at least two previous image frames, where the firstimage frame includes the image in the first screen area; determine afirst detection area in the first image frame according to the motiontendency; and detect whether the first laser point exists in the firstdetection area. When the first laser point exists in the first detectionarea, the first laser point exists in the first image frame.

In another embodiment, the detection module 802 is configured to detectwhether a first pixel exists in the first detection area, where pixelsconstituting the first laser point include the first pixel; andcorrespondingly, the second acquiring module 803 is configured todetermine a second detection area in the first image frame according toinformation about a location of the first pixel in the first imageframe; detect a second pixel in the second detection area, where thepixels constituting the first laser point include the second pixel, andacquire information about a location of the second pixel in the firstimage frame; and acquire the information about the location of the firstlaser point on the screen according to the information about thelocation of the second pixel in the first image frame.

In another embodiment, the detection module 802 is configured todetermine a scanning area in the first image frame; perform downsamplingon the scanning area by using m rows as a vertical sampling interval andn columns as a horizontal sampling interval to obtain a downsamplingresult, where m is a positive integer, and n is a positive integer; anddetect whether the first laser point exists in the downsampling result.When the first laser point exists in the downsampling result, the firstlaser point exists in the first image frame.

In a specific implementation process, the detection module 802 maycombine and implement two detection methods as described in the methodembodiments, and details are not described herein again.

Further, the downsampling result includes a low-resolution image frameobtained after downsampling is performed on the first image frame.Correspondingly, the second acquiring module 803 is configured toacquire information about a low-resolution location of the first laserpoint in the low-resolution image frame; determine a potential area inthe first image frame, where the potential area corresponds to theinformation about the low-resolution location; detect the first laserpoint in the potential area, and acquire information about a location ofthe first laser point in the first image frame; and acquire theinformation about the location of the first laser point on the screenaccording to the information about the location of the first laser pointin the first image frame.

In another embodiment, the second acquiring module 803 is furtherconfigured to, when a second laser point exists in a second image framecaptured by a second camera among the N cameras, acquire informationabout a location, on the screen, of the laser point on the screenaccording to the first laser point and the second laser point.

The second acquiring module 803 may be configured to determine the laserpoint on the screen from the first laser point detected by the detectionmodule and the second laser point; and acquire the information about thelocation, on the screen, of the laser point on the screen.

Further, the second acquiring module 803 is configured to, when thelaser points exist in the at least two previous image frames of thefirst image frame that is captured by the first camera, use the firstlaser point as the laser point on the screen when the motion tendency ofthe laser point in the first screen area among the N screen areas isfrom the first screen area to a second screen area among the N screenareas, where the motion tendency is obtained according to theinformation about the locations of the laser points in the at least twoprevious image frames, the first image frame includes the image in thefirst screen area, and the second image frame includes an image in thesecond screen area; or use the second laser point as the laser point onthe screen when the motion tendency is from a second screen area to thefirst screen area.

The second acquiring module 803 may further be configured to determinewhether the first laser point and the second laser point are a samelaser point according to first location information of the first laserpoint detected by the detection module and second location informationof the second laser point, where the first location information is theinformation about the location of the first laser point in the firstimage frame, the second location information is information about alocation of the second laser point in the second image frame, the secondimage frame includes the image in the second screen area among the Nscreen areas, the first image frame includes the image in the firstscreen area among the N screen areas, and the second screen area isadjacent to the first screen area; and when the first laser point andthe second laser point are the same laser point, acquire the informationabout the location, on the screen, of the laser point on the screenaccording to the first location information and the second locationinformation.

The N screen areas are N subscreens, and the screen is a splicedprojection screen including the N subscreens. Optionally, the Nsubscreens receive images projected by N projection devices, where the Nprojection devices correspond to the N subscreens in a one-to-onemanner. In addition, the N cameras capture images on the N subscreens.In such a screen system, the N cameras capture the images on the Nsubscreens at the same time to ensure accuracy of subsequently acquiredlaser point coordinates and further reduce time for subsequentcoordinate fusion.

Reference may be made to the foregoing method embodiments, and detailsare not described herein again.

If the apparatus is applied to a short-focus projection screen system,that is, a camera is extremely near a screen, an image needs to becaptured by using a wide-angle camera for a purpose of acquiring a morecomplete and accurate image.

FIG. 9 is a schematic structural diagram of Embodiment 2 of an apparatusfor detecting a location of a laser point on a screen according to thepresent application. As shown in FIG. 9, based on FIG. 8, the apparatusfor detecting a location of a laser point on a screen may furtherinclude a calibration module 804 configured to calibrate the firstlocation information to calibrate a distortion resulting from thewide-angle camera, so that the second acquiring module 803 acquires theinformation about the location, on the screen, of the laser point on thescreen according to the calibrated location information, where the firstlocation information is the information about the location of the firstlaser point in the first image frame.

An implementation principle and a technical effect of the apparatus aresimilar to those of the method and are not described herein again.

FIG. 10 is a schematic structural diagram of Embodiment 3 of anapparatus for detecting a location of a laser point on a screenaccording to the present application. The apparatus is applied to ascreen projection system, and the system includes a screen and Ncameras, where the screen includes N screen areas, the N cameras areused to capture images in the N screen areas, the screen areascorrespond to the cameras in a one-to-one manner, and N is a positiveinteger greater than 1. As shown in FIG. 10, the apparatus includes amemory 901 and a processor 902.

The memory 901 is configured to store a program instruction, and theprocessor 902 is configured to invoke the program instruction in thememory 901 to perform a method that includes acquiring a first imageframe captured by a first camera among the N cameras; detecting whethera first laser point exists in the first image frame; and when the firstlaser point exists in the first image frame, and no laser point existsin an image frame captured by another camera except the first cameraamong the N cameras, using the first laser point as a laser point on thescreen, and acquiring information about a location of the first laserpoint on the screen. In this embodiment, a first image frame captured bya first camera is acquired; whether a first laser point exists in thefirst image frame is detected; and when the first laser point exists inthe first image frame, and no laser point exists in an image captured byanother camera except the first camera among N cameras, it is determinedthat the first laser point is a laser point on a screen, and informationabout a location of the first laser point on the screen is acquired.That is, images captured by all cameras do not need to be fused first;instead, laser point detection is directly performed on a captured imageframe. This greatly improves efficiency of the laser point detection andimproves detection accuracy.

Further, the processor 902 is configured to, when laser points exist inat least two previous image frames of the first image frame, determine amotion tendency of a laser point in a first screen area among the Nscreen areas according to information about locations of the laserpoints in the at least two previous image frames, where the first imageframe includes an image in the first screen area; determine a firstdetection area in the first image frame according to the motiontendency; and detect whether the first laser point exists in the firstdetection area. When the first laser point exists in the first detectionarea, the first laser point exists in the first image frame.

The detecting whether the first laser point exists in the firstdetection area may be detecting whether a first pixel exists in thefirst detection area, where pixels constituting the first laser pointinclude the first pixel; and correspondingly, the acquiring informationabout a location of the first laser point on the screen may bedetermining a second detection area in the first image frame accordingto information about a location of the first pixel in the first imageframe; detecting a second pixel in the second detection area, where thepixels constituting the first laser point include the second pixel, andacquiring information about a location of the second pixel in the firstimage frame; and acquiring the information about the location of thefirst laser point on the screen according to the information about thelocation of the second pixel in the first image frame.

In another embodiment, the processor 902 is configured to determine ascanning area in the first image frame; perform downsampling on thescanning area by using m rows as a vertical sampling interval and ncolumns as a horizontal sampling interval to obtain a downsamplingresult, where m is a positive integer, and n is a positive integer; anddetect whether the first laser point exists in the downsampling result.

The downsampling result includes a low-resolution image frame obtainedafter downsampling is performed on the first image frame. The processor902 is configured to acquire information about a low-resolution locationof the first laser point in the low-resolution image frame; determine apotential area in the first image frame, where the potential areacorresponds to the information about the low-resolution location; detectthe first laser point in the potential area, and acquire informationabout a location of the first laser point in the first image frame; andacquire the information about the location of the first laser point onthe screen according to the information about the location of the firstlaser point in the first image frame.

Further, the processor 902 is further configured to, when a second laserpoint exists in a second image frame captured by a second camera amongthe N cameras, acquire information about a location, on the screen, ofthe laser point on the screen according to the first laser point and thesecond laser point.

The acquiring information about a location, on the screen, of the laserpoint on the screen according to the first laser point and the secondlaser point may be determining the laser point on the screen from thefirst laser point and the second laser point; and acquiring theinformation about the location, on the screen, of the laser point on thescreen.

When the laser points exist in the at least two previous image frames ofthe first image frame that is captured by the first camera, thedetermining, by the processor 902, the laser point on the screen fromthe first laser point and the second laser point is as follows. Theprocessor 902 uses the first laser point as the laser point on thescreen when the motion tendency of the laser point in the first screenarea among the N screen areas is from the first screen area to a secondscreen area among the N screen areas, where the motion tendency isobtained according to the information about the locations of the laserpoints in the at least two previous image frames, the first image frameincludes the image in the first screen area, and the second image frameincludes an image in the second screen area; or uses the second laserpoint as the laser point on the screen when the motion tendency is fromthe second screen area to the first screen area.

The acquiring, by the processor 902, information about a location, onthe screen, of the laser point on the screen according to the firstlaser point and the second laser point may further be determiningwhether the first laser point and the second laser point are a samelaser point according to first location information of the first laserpoint and second location information of the second laser point, wherethe first location information is the information about the location ofthe first laser point in the first image frame, the second locationinformation is information about a location of the second laser point inthe second image frame, the second image frame includes an image in asecond screen area among the N screen areas, the first image frameincludes the image in the first screen area among the N screen areas,and the second screen area is adjacent to the first screen area; andwhen the first laser point and the second laser point are the same laserpoint, acquiring the information about the location, on the screen, ofthe laser point on the screen according to the first locationinformation and the second location information.

The N screen areas may be N subscreens, and the screen is a splicedprojection screen including the N subscreens. Optionally, the Nsubscreens receive images projected by N projection devices, where the Nprojection devices correspond to the N subscreens in a one-to-onemanner. In addition, the N cameras capture images on the N subscreens.In such a screen system, the N cameras capture the images on the Nsubscreens at the same time to ensure accuracy of subsequently acquiredlaser point coordinates and further reduce time for subsequentcoordinate fusion.

If the camera is a wide-angle camera, the processor 902 is furtherconfigured to, before acquiring the information about the location ofthe first laser point on the screen, calibrate the first locationinformation to calibrate a distortion resulting from the wide-anglecamera, so that the information about the location, on the screen, ofthe laser point on the screen is acquired according to the calibratedlocation information, where the first location information is theinformation about the location of the first laser point in the firstimage frame.

FIG. 11 is a schematic structural diagram of Embodiment 1 of a screenprojection system according to the present application. As shown in FIG.11, the system may include a screen 01, the apparatus 03 for detecting alocation of a laser point on a screen, and N cameras 04, where N is apositive integer greater than 1; the screen 01 includes N screen areas11, the N cameras 04 capture images in the N screen areas, and thescreen areas correspond to the cameras in a one-to-one manner. In FIG.10, N=3 is used as an example.

The system further includes a projection device 02, where the projectiondevice 02 projects an image onto the screen 01. One or more projectiondevices may be available. A specific quantity may be set according to anactual need, which is not limited herein.

The system may further include a laser pointer, where the laser pointerprojects a laser point onto the screen.

The system may further include N projection devices. The N screen areasare N subscreens, and the screen is a spliced projection screenincluding the N subscreens. The subscreens correspond to the projectiondevices in a one-to-one manner, and no overlapping area exists betweenrespective projection areas of the N projection devices. Each of thesubscreens may be enclosed in a projection device corresponding to eachof the subscreens, so that no light travels in space between the projectdevice and another subscreen.

Referring to FIG. 11, the system may further include a synchronizationapparatus 05 configured to connect to the N cameras, and thesynchronization apparatus is configured to control the N cameras tocapture the images in the N screen areas at the same time.

No overlapping area may exist between respective images captures by theN cameras. Each of the subscreens may be enclosed in a cameracorresponding to each of the subscreens, so that no light travels inspace between the camera and another subscreen.

The apparatus 03 for detecting a location of a laser point on a screenin the system is the apparatus for detecting a location of a laser pointon a screen in the foregoing embodiment, implementation principles andtechnical effects of both apparatuses are similar and are not describedherein again.

The synchronization apparatus 05 may send a pulse message to the Ncameras 04 at the same time, so as to trigger the N cameras 04 tocapture images on the N subscreens at the same time, which, however, isnot limited herein.

In the several embodiments provided in the present application, itshould be understood that the disclosed apparatus and method may beimplemented in other manners. For example, the described apparatusembodiment is merely exemplary. For example, the unit division is merelylogical function division and may be other division in actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not performed. In addition, the displayed or discussed mutualcouplings or direct couplings or communication connections may beimplemented by using some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one location, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected according toactual needs to achieve the objectives of the solutions of theembodiments.

In addition, functional units in the embodiments of the presentapplication may be integrated into one processing unit, or each of theunits may exist alone physically, or two or more units are integratedinto one unit. The integrated unit may be implemented in a form ofhardware, or may be implemented in a form of hardware in addition to asoftware functional unit.

When the foregoing integrated unit is implemented in a form of asoftware functional unit, the integrated unit may be stored in acomputer-readable storage medium. The software functional unit is storedin a storage medium and includes several instructions for instructing acomputer device (which may be a personal computer, a server, or anetwork device) or a processor to perform some of the steps of themethods described in the embodiments of the present application. Theforegoing storage medium includes any medium that can store programcode, such as a universal serial bus (USB) flash drive, a removable harddisk, a read-only memory (ROM), a random access memory (RAM), a magneticdisk, or an optical disc.

Finally, it should be noted that the foregoing embodiments are merelyintended for describing the technical solutions of the presentapplication, but not for limiting the present application. Although thepresent application is described in detail with reference to theforegoing embodiments, persons of ordinary skill in the art shouldunderstand that they may still make modifications to the technicalsolutions described in the foregoing embodiments or make equivalentreplacements to some or all technical features thereof, withoutdeparting from the scope of the technical solutions of the embodimentsof the present application.

What is claimed is:
 1. A method for detecting a location of a laserpoint on a screen of a screen projection system, the method comprising:acquiring a first image frame captured by a first camera of a pluralityof cameras, each of the plurality of cameras configured to capture animage in an associated one of a corresponding plurality of screen areasof a screen; detecting whether a first laser point projected on thescreen by a laser pointer exists in the first image frame; using thefirst laser point as a laser point on the screen when the first laserpoint exists in the first image frame and no laser point exists in animage frame captured by any camera of the plurality of cameras otherthan the first camera; and acquiring information about a location of thefirst laser point on the screen.
 2. The method according to claim 1,wherein when laser points exist in at least two previous image frames ofthe first image frame, detecting whether the first laser point exists inthe first image frame comprises: determining a motion tendency of alaser point in a first screen area in the plurality of screen areasaccording to information about locations of laser points in the at leasttwo previous image frames, the first image frame comprising an image inthe first screen area; determining a first detection area in the firstimage frame according to the motion tendency; and detecting whether thefirst laser point exists in the first detection area.
 3. The methodaccording to claim 2, wherein: detecting whether the first laser pointexists in the first detection area comprises detecting whether a firstpixel exists in the first detection area, pixels constituting the firstlaser point comprising the first pixel; and acquiring the informationabout the location of the first laser point on the screen comprises:determining a second detection area in the first image frame accordingto information about a location of the first pixel in the first imageframe; detecting a second pixel in the second detection area, the pixelsconstituting the first laser point comprising the second pixel;acquiring information about a location of the second pixel in the firstimage frame; and acquiring the information about the location of thefirst laser point on the screen according to the information about thelocation of the second pixel in the first image frame.
 4. The methodaccording to claim 1, wherein detecting whether the first laser pointexists in the first image frame comprises: determining a scanning areain the first image frame; performing downsampling on the scanning areaby using m rows as a vertical sampling interval and n columns as ahorizontal sampling interval to obtain a downsampling result, m being apositive integer and n being a positive integer; and detecting whetherthe first laser point exists in the downsampling result.
 5. The methodaccording to claim 4, wherein the downsampling result comprises alow-resolution image frame obtained after the downsampling is performedon the scanning area, and acquiring the information about the locationof the first laser point on the screen comprises: acquiring informationabout a low-resolution location of the first laser point in thelow-resolution image frame; determining a potential area in the firstimage frame, the potential area corresponding to the information aboutthe low-resolution location detecting the first laser point in thepotential area; acquiring information about a location of the firstlaser point in the first image frame; and acquiring the informationabout the location of the first laser point on the screen according tothe information about the location of the first laser point in the firstimage frame.
 6. The method according to claim 1, the method furthercomprising acquiring information about a location of the laser point onthe screen according to the first laser point and a second laser pointwhen the second laser point exists in a second image frame captured by asecond camera of the plurality of cameras.
 7. The method according toclaim 6, wherein acquiring the information about the location of thelaser point on the screen according to the first laser point and thesecond laser point comprises: determining the laser point on the screenfrom the first laser point and the second laser point; and acquiring theinformation about the location of the laser point on the screen.
 8. Themethod according to claim 7, wherein when laser points exist in at leasttwo previous image frames of the first image frame, determining thelaser point on the screen from the first laser point and the secondlaser point comprises: using the first laser point as the laser point onthe screen when a motion tendency of the laser point in the first screenarea among the plurality of screen areas is from the first screen areato a second screen area among the plurality of screen areas, the motiontendency being obtained according to the information about the locationsof the laser points in the at least two previous image frames, the firstimage frame comprising the image in the first screen area, and thesecond image frame comprising an image in the second screen area; orusing the second laser point as the laser point on the screen when themotion tendency is from a second screen area to the first screen area.9. The method according to claim 6, wherein acquiring the informationabout the location of the laser point on the screen according to thefirst laser point and the second laser point comprises: determiningwhether the first laser point and the second laser point are a samelaser point according to first location information of the first laserpoint and second location information of the second laser point, thefirst location information being information about a location of thefirst laser point in the first image frame, the second locationinformation being information about a location of the second laser pointin the second image frame, the second image frame including an image ina second screen area among the plurality of screen areas, the firstimage frame including an image in a first screen area among theplurality of screen areas, and the second screen area being adjacent tothe first screen area; and acquiring the information about the locationof the laser point on the screen according to the first locationinformation and the second location information when the first laserpoint and the second laser point are the same laser point.
 10. Themethod according to claim 1, wherein the first camera is a wide-anglecamera, and before acquiring the information about the location of thefirst laser point on the screen, the method further comprisescalibrating a first location information to calibrate a distortionresulting from the wide-angle camera, so that the information about thelocation of the laser point on the screen is acquired according to thecalibrated first location information, wherein the first locationinformation is information about the location of the first laser pointin the first image frame.
 11. An apparatus for detecting a location of alaser point on a screen, the apparatus comprising: a memory storinginstructions; and a processor coupled to the memory and configured toexecute the instructions to: acquire a first image frame captured by afirst camera of a plurality of cameras, each of the plurality of camerasconfigured to capture an image in an associated one of a correspondingplurality of screen areas of a screen; detect whether a first laserpoint projected on the screen by a laser pointer exists in the firstimage frame; use the first laser point as a laser point on the screenwhen the first laser point exists in the first image frame and no laserpoint exists in an image frame captured by any camera of the pluralityof cameras other than the first camera; and acquire information about alocation of the first laser point on the screen.
 12. The apparatusaccording to claim 11, wherein the processor is configured to: determinea motion tendency of a laser point in a first screen area in theplurality of screen areas according to information about locations oflaser points in at least two previous image frames when the laser pointsexist in the at least two previous image frames of the first imageframe, the first image frame comprising an image in the first screenarea; determine a first detection area in the first image frameaccording to the motion tendency; and detect whether the first laserpoint exists in the first detection area.
 13. The apparatus according toclaim 12, the processor is configured to: detect whether a first pixelexists in the first detection area, pixels constituting the first laserpoint comprising the first pixel; determine a second detection area inthe first image frame according to information about a location of thefirst pixel in the first image frame; detect a second pixel in thesecond detection area, the pixels constituting the first laser pointcomprising the second pixel; acquire information about a location of thesecond pixel in the first image frame; and acquire the information aboutthe location of the first laser point on the screen according to theinformation about the location of the second pixel in the first imageframe.
 14. The apparatus according to claim 11, wherein the processor isconfigured to: determine a scanning area in the first image frame;perform downsampling on the scanning area by using m rows as a verticalsampling interval and n columns as a horizontal sampling interval toobtain a downsampling result, m being a positive integer and n being apositive integer; and detect whether the first laser point exists in thedownsampling result.
 15. The apparatus according to claim 14, whereinthe downsampling result comprises a low-resolution image frame acquiredafter the downsampling is performed on the scanning area, and whereinthe processor is configured to: acquire information about alow-resolution location of the first laser point in the low-resolutionimage frame; determine a potential area in the first image frame,wherein the potential area corresponds to the information about thelow-resolution location; detect the first laser point in the potentialarea; acquire information about a location of the first laser point inthe first image frame; and acquire the information about the location ofthe first laser point on the screen according to the information aboutthe location of the first laser point in the first image frame.
 16. Theapparatus according to claim 11, wherein the processor is furtherconfigured to acquire information about a location of the laser point onthe screen according to the first laser point and a second laser pointwhen the second laser point exists in a second image frame captured by asecond camera of the plurality of cameras.
 17. A screen projectionsystem, comprising: a screen, comprising a plurality of screen areas; anapparatus for detecting a location of a laser point projected on thescreen by a laser pointer; and a plurality of cameras, each configuredto capture an image in a corresponding one of the plurality of screenareas, wherein the apparatus for detecting the location of the laserpoint on the screen comprises: a memory storing instructions; and aprocessor coupled to the memory and configured to execute theinstructions to: acquire a first image frame captured by a first cameraof a plurality of cameras, each of the plurality of cameras configuredto capture an image in an associated one of a corresponding plurality ofscreen areas of a screen; detect whether a first laser point projectedon the screen by a laser pointer exists in the first image frame; usethe first laser point as a laser point on the screen when the firstlaser point exists in the first image frame and no laser point exists inan image frame captured by any camera of the plurality of cameras otherthan the first camera; and acquire information about a location of thefirst laser point on the screen.
 18. The system according to claim 17,wherein the system comprises a plurality of projection devices, theplurality of screen areas being a plurality of subscreens, the screenbeing a spliced projection screen comprising the plurality ofsubscreens, the plurality of subscreens corresponding to the pluralityof projection devices in a one-to-one manner, and no overlapping areaexisting between respective projection areas of the plurality ofprojection devices.
 19. The system according to claim 17, wherein thesystem further comprises a synchronization apparatus configured toconnect to the plurality of cameras, the synchronization apparatus beingconfigured to control the plurality of cameras to capture the images inthe plurality of screen areas at the same time.
 20. The system accordingto claim 17, wherein no overlapping area exists between the respectiveimages captured by the plurality of cameras.